Fix demanded bits analysis with srem by negative number. Based on a patch
by Richard Osborne.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58555 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 75a1ffe..3210b12 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1274,12 +1274,12 @@
break;
case Instruction::SRem:
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
- APInt RA = Rem->getValue();
- if (RA.isPowerOf2() || (-RA).isPowerOf2()) {
+ APInt RA = Rem->getValue().abs();
+ if (RA.isPowerOf2()) {
if (DemandedMask.ule(RA)) // srem won't affect demanded bits
return UpdateValueUsesWith(I, I->getOperand(0));
- APInt LowBits = RA.isStrictlyPositive() ? (RA - 1) : ~RA;
+ APInt LowBits = RA - 1;
APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
if (SimplifyDemandedBits(I->getOperand(0), Mask2,
LHSKnownZero, LHSKnownOne, Depth+1))